Application of PSS to Improve the Stability of a Power System With a High Penetration of Renewable Energy

Unlike traditional power generation composed of synchronous generators, renewable energy in theform of solar and wind power does not add inertia to power systems. Therefore, as increasedproportions of renewable energy are added, the dynamics of the power system will be affected. In thisreport it is examined how power system stability can be improved when increasing amounts ofconverter-based renewable energy are introduced to Kundur's two-area system. The effects ontransient and small-signal stability are characterised and compared to a fully non-renewable systemusing the simulation programme SIMPOW. Thereafter, a power system stabiliser (PSS) based on acontrol-Lyapunov function (CLF) algorithm is utilised to improve power system stability anddamping. A methodology is developed to find a PSS tuning which suits varying placements andproportions of renewable energy throughout the system. Finally, the effects of adding a second PSSare examined and compared with those for a single PSS. The introduction of PSS tuned with thedeveloped methodology shows promise in improving system stability when renewable power sourcesare introduced. Future work may be directed into applying the methods presented on a larger grid, aswell further exploring the characteristics of a CLF-based approach. ; Till skillnad från traditionell elektricitetsgenerering som förlitar sig på synkrongeneratorer såintroducerar förnybar energi i form av vind- och solkraft inte svängmassa till elnätet. När andelenförnybar kraft i systemet ökar kommer därför kraftsystemsdynamiken att påverkas. I denna rapportstuderas hur kraftsystemsstabiliteten kan förbättras när en ökande andel omriktarbaserad förnybarenergi introduceras till Kundurs två-områdessystem. Effekterna på transient och småsignalsstabilitetkaraktäriseras och jämförs med motsvararande system helt utan omriktarbaserad kraftgenerering isimuleringsprogramet SIMPOW. Därefter introduceras en kraftsystemstabilisator (PSS) baserad på enkontroll-Lyapunovfunktionsalgoritm (CLF) för att förbättra ...